The photonic snake, a new instrument to reveal the secrets of light

Light, with its innumerable colors, is one of the wonders of nature. To really understand what we see, it is essential to know the color of light with which we perceive our world. An ideal way to achieve this, thanks to modern technology, is through optical rules called frequency combs (frequency combs in English) and whose application earned the Nobel Prize in Physics in 2005.

With the optical rulers, not only colors are measured, but also times, distances and other essential magnitudes; hence its importance in scientific and technological applications is enormous. They are the tools that allow you to enter the kingdom of light and reveal its deepest secrets. A recent study carried out by a team led by the Polytechnic University of Valencia (UPV), and headed by Salim B. Ivars, from the UPV and the Polytechnic University of Catalonia (UPC) allows precisely one more step. . Lluís Torner, director of the Institute of Photonic Sciences (ICFO), linked to the UPC, as well as Yaroslav V. Kartashov, a researcher at the Institute of Spectroscopy of the Russian Academy of Sciences in Moscow, also participated.

The authors of the new study have discovered the “photonic snake states”, a new instrument to unravel, even more, the secrets of light, since it opens up unprecedented perspectives on the formation of the combs of frequency: predicts the existence of two-dimensional optical rules, more complex than the one-dimensional ones handled so far, and provide unprecedented versatility in a wide range of applications. The study has captured the attention of the international scientific community.

Applications in communications, spectroscopy, or computing

The uses of frequency combs are very varied, and they stand out above all in the field of communications. These combs make it possible to transmit large amounts of information through optical fibers very efficiently, since, having well-defined frequencies, multiple light signals can be sent at the same time and easily separated when received.

Another area where frequency combs have shown great utility is in spectroscopy. By being able to obtain optical spectra with unprecedented precision and resolution, the identification of different chemical substances is facilitated. This has direct application in fields such as chemistry, biology and medicine, where the precise detection of molecules and the characterization of materials is essential.

In the case of metrology, the science of measurement, these structures are used as a reference to define standards, thanks to their ability to generate stable and known frequencies. This allows very precise measurements in fundamental quantities, such as time or length, relevant to most scientific fields.

Finally, frequency combs have also found promising applications in quantum computing, where light particles (or photons) play a key role. Specifically, frequency combs can be used to generate individual photons with specific properties, which is crucial for the development of these technologies.

Graphic representation of a photonic microcylinder in photonic snake generation regime. (Image: UPV)

The future of optical rulers

A fundamental problem that must be analyzed in order to be successful in these proposals is that of the instabilities that appear when trying to build these optical rulers and that prevent versatile forms of light from being generated. As Professor Pedro Fernández de Córdoba, a researcher at the University Institute of Pure and Applied Mathematics (IUMPA) of the UPV and co-author of this work, points out, “it should be noted that our team has obtained, from a theoretical point of view, the conditions for that the structure of light is stable, finding zig-zag configurations that we have called Photonic Serpents. The stability of these light states is a crucial aspect for future applications.”

Likewise, in this study it has been shown that it is possible to create a two-dimensional arrangement of optical rulers synchronized with each other and individually accessible. This discovery provides a comprehensive collection of rules generated on a single device and controlled by a single laser light source. In fact, as Professor Carles Milián, co-author of the study, states: “the potential impact of this advance is extraordinary, since it could allow the development of reconfigurable and broadband monolithic multicomb devices. These devices would supply different frequency combs on demand and in real time, significantly expanding existing applications.”

Finally, this study has been based on rigorous and very complete theoretical models, which have taken into account all the known effects that could appear in future experiments on the formation of two-dimensional frequency combs, and which have been simulated using powerful theoretical tools and numeric. In fact, as Professor J. Alberto Conejero, director of the Department of Applied Mathematics at the UPV and co-author of this work, points out, “in this research a very precise model has been built that includes all the phenomena that can influence the formation of these structures. It will work as a guide for future experiments, with the consequent economic impact by knowing in advance the experimental parameters with which stable light snakes can be generated.”

For the director of ICFO, Lluís Torner, “this important discovery is remarkable for being unexpected and surprising, and it has been possible thanks to the intuition and leadership of Professor Milián.”

The UPV, UPC and ICFO team assures that this finding will further stimulate research in the field and will lead to new applications and revolutionary technologies. “Thanks to these advances, we are one step closer to unraveling the mysteries of light and taking advantage of its full potential for the benefit of our society,” they conclude.

The study is titled “Photonic snake states in two-dimensional frequency combs”. And it has been published in the academic journal Nature Photonics. (Source: UPC)